The present invention is concerned with bandages and other treatment membranes for mammals, especially for dental applications in the oral cavity or mouth to be mechanically retained in position by the teeth in humans. The treatment membrane is contemplated to have medical applications beyond dentistry.
Periodontal diseases and other dental diseases and difficulties affect a significant percentage of the population, causing defects in bony supportive structure of teeth and deterioration of the attachement of the tooth to soft tissue. It is often necessary to conduct one or more forms of surgery to correct anatomical defects which are the consequence of the disease, or to eliminate the microbiological milieu which is responsible for the progression of the disease. Thus, surgically removing soft tissue or bone may be a treatment to allow better access for plaque removal by the patient; or tooth substance and adjacent tissue may be surgically removed to eliminate the microbiological infection; or teeth and adjacent tissue may be surgically removed to prepare for dentures or as a consequence of carious destruction of the natural dentition. In many of these cases a dressing is desirably placed to protect the defect or wound site, for example, protecting soft tissue and sutures after surgery.
Present dressings are typified by combinations of metallic oxides and organic acids that are mixed together immediately prior to use, most frequently as two pastes which react in-situ to form hard, brittle, opaque compounds. Frequently one of the reactants is weakly acidic, a carboxylic acid or a phenolic compound, e.g. eugenol, or the like. The weak salts that form and are the structural basis of the compound are hydrolytically unstable. Saliva may leach these reactants as they hydrolyze. In due course the products crumble and disintegrate and the patients swallow or expectorate the fragments. The leached structural products frequently are unpleasant tasting and are otherwise undesirable.
Another class of compounds relies on the reaction of calcium sulfate hemihydrate, dispersed in a water permeable mixture of precured polymer and solvent. Sometimes the compounds contain inert filler, and water from the saliva is used to react with the calcium sulfate hemihydrate to form gypsum. This reaction occurs relatively slowly, and frequently the products are disintegrated before they can carry out their requisite protective function.
Yet another class of prior known materials is the combination of a polymer, polyethyl methacrylate and a solvent mixture frequently comprising a plasticizer such as esters of phthalic acid and ethanol. The plasticized pseudoelastomer which forms as the polymer solvates has poor elastic properties and develops slowly. The progression to adequately high viscosity requires from 10 to 30 minutes. No polymerization occurs. As the alcohol and plasticizer are eluted in time in the mouth the mixture becomes increasingly hard.
Each of these materials depend on the reaction, (for purposes of this discussion the solvation of a polymer by a solvent is classified as a reaction), between two or more previously separated components which are combined together and allowed to harden in-situ. In the first case, metal ions and organic carboxylic acids or phenolic compounds react, in the second case calcium sulfate hemihydrate and water (saliva); and in the third case, polymer powder and solvent.
It is an object of the present invention to provide methods and materials that overcome the deficiencies of the known dental wound dressings: to provide new methods and materials that provide treatment membranes that are long lasting and resist destruction between dental appointments, and are easy and quick to apply with good retentive properties and are useful for wound dressings, stents and other treatment purposes.
Another object of the present invention is to obviate the need for two separate components, and to obviate the time delay and inconvenience which are a consequence of mixing and having them react at their pretimed schedule within the mouth.
Another object is to provide a treatment membrane material that is fluid and has adequate manipulation time after placement to allow adapting the treatment membrane material to the site to be treated and then provides a means for quickly setting the fluid to convert the fluid to a solid.
Yet another object is to permit prepackaging of a bandage, especially of the wound or periodontal dressing type, within a syringe from which the wound dressing can be extruded inter-dentinally for mechanical retention, and directly upon a wound surface as required.
Another object is the provision of a bandage which may be mechanically retained by etched patterns in the enamal of teeth.
A further object of the invention is to provide a treatment membrane that is pigmented so as to be aesthetically less noticeable when in place in the oral cavity (mouth) of a patient.
Another object is to provide a treatment membrane that is translucent or clear, allowing inspection of the wound site without removal of the membrane.
Yet a further object is to provide a treatment membrane in a preferred form that is resilient and non hardening and thereby gentler to soft tissue with which it is in contact, an aid to patient comfort and aids in the longevity of the treatment membrane in the hostile environment of the oral cavity.
A further object is to provide a treatment membrane that is moisture resistant and non-fouling.
A still further object of the invention is to provide a treatment membrane that yields a continuing dose of therapeutic material over a period of time.